Disk pack assemblies typically comprise a memory unit including a plurality of disks with magnetizable coatings, mounted in spaced relationship on a hub, and a central axle rotatably mounted in the center of the hub which serves as a bolt to attach the memory unit to a disk drive. Also included are top and bottom cover assemblies which mate around and protect the memory unit when it is not being utilized on a disk drive. The bottom cover assembly includes a latch which releasably engages the hub to hold the bottom cover assembly in place and can be manually released from outside the bottom cover so that the bottom cover assembly can be removed to expose the hub and axle for engagement with the disk drive. The top cover assembly includes a handle having a stem portion with a socket adapted to closely receive an upper portion of the axle and having axially projecting pins on its end adapted to engage openings on a generally central, radially projecting flange on the axle so that a transverse portion of the handle can be manually engaged and the handle can be used as a wrench to rotate the axle into or out of engagement with a disk drive. The axle also has a mechanism which will normally hold locking elements or ball bearings mounted in the portion of the axle which is received in the socket of the handle, in a position projecting outwardly from the surface of the axle. A portion of the socket has an increased diameter capable of receiving the axle when the ball bearings are projecting therefrom. An adjacent inwardly projecting lip around the opening of the socket prevents movement of the axle out of the socket as long as the ball bearings are projecting therefrom. This mechanism thereby maintains the top cover assembly in engagement with the memory unit and allows the memory unit to be carried via the handle. The mechanism is operated by a projection on the disk drive that allows the ball bearings to retract into the axle when the axle is engaged on a disk drive. The handle (and thereby the top cover) is thereby automatically released from the memory unit as the memory unit is secured to a disk drive.
Heretofore, in order to provide the inner wall surface defining the socket, including the inwardly projecting lip at the opening of the socket, the area of increased diameter within the socket adjacent the lip that receives the ball bearings from the axle, and a smaller diameter innermost portion of the socket that closely receives the uppermost portion of the axle, the surface had to be machined in a first part of the handle, a second part which provides the innermost portion of the socket and a portion adapted for manual engagement was then molded around the machined part.